Add missing compiler errors CS8954–CS8956 to using-directive-errors doc

docs/core/docker/snippets/App/Program.cs

@@ -1,9 +1,17 @@
 var counter = 0;
-var max = args.Length is not 0 ? Convert.ToInt32(args[0]) : -1;
 
-while (max is -1 || counter < max)
+// If a number is passed as a command-line argument,
+// it will be used as the maximum counter value.
+var max = args.Length > 0 && int.TryParse(args[0], out var parsedMax)
+    ? parsedMax
+    : -1;
+
+// Run indefinitely if no max value is provided
+while (max == -1 || counter < max)
 {
-    Console.WriteLine($"Counter: {++counter}");
+    counter++;
+    Console.WriteLine($"Counter: {counter}");
 
-    await Task.Delay(TimeSpan.FromMilliseconds(1_000));
-}
+    // Wait for one second between iterations
+    await Task.Delay(TimeSpan.FromSeconds(1));
+}

docs/csharp/language-reference/compiler-messages/using-directive-errors.md

@@ -20,6 +20,9 @@ f1_keywords:
   - "CS8914"
   - "CS8915"
   - "CS8933"
+  - "CS8954"
+  - "CS8955"
+  - "CS8956"
   - "CS9130"
   - "CS9131"
   - "CS9132"
@@ -44,6 +47,9 @@ helpviewer_keywords:
   - "CS8914"
   - "CS8915"
   - "CS8933"
+  - "CS8954"
+  - "CS8955"
+  - "CS8956"
   - "CS9130"
   - "CS9131"
   - "CS9132"
@@ -71,6 +77,9 @@ That's be design. The text closely matches the text of the compiler error / warn
 - [**CS8085**](#restrictions-on-using-aliases): *Error: A 'using static' directive cannot be used to declare an alias.*
 - [**CS8914**](#global-using-directive): *Error: A global using directive cannot be used in a namespace declaration.*
 - [**CS8915**](#global-using-directive): *Error: A global using directive must precede all non-global using directives.*
+- [**CS8954**](#global-using-directive): *Error: A global using directive must precede all non-global using directives.*
+- [**CS8955**](#global-using-directive): *Error: A file-local type cannot be used in a global using directive.*
+- [**CS8956**](#using-directive-placement): *Error: A using directive must precede all other elements defined in the namespace except extern alias declarations.*
 - [**CS9130**](#restrictions-on-using-aliases): *Error: Using alias cannot be a `ref` type.*
 - [**CS9131**](#restrictions-on-using-aliases): *Error: Only a using alias can be `unsafe`.*
 - [**CS9132**](#restrictions-on-using-aliases): *Error: Using alias cannot be a nullable reference type.*
@@ -107,6 +116,10 @@ The compiler produces warning **CS8933**, **CS0105** or diagnostic **CS8019** fo
 
 Incorrectly combining a `using` directive with the `static`, `global`, or `unsafe` modifiers on a `using` directive are covered later in this article.
 
+The compiler also produces **CS8956** when a using directive doesn't appear before other elements defined in a namespace (except extern alias declarations).
+
+
+
 ## Using static directive
 
 The `using static` directive imports one type's members into the current namespace. The following example imports the methods from `System.Console`, such as `WriteLine` into the current namespace:
@@ -141,6 +154,15 @@ Any `global using` directives must precede any non-global `using` directives in
 
 Furthermore, a `static global using` directive can't reference a [file-local](../keywords/file.md) type.
 
+Violating these rules can also produce the following errors:
+
+### CS8954
+A global using directive must precede all non-global using directives.
+
+### CS8955
+A file-local type cannot be used in a global using directive.
+
+
 ## Alias qualifier
 
 The alias qualifier, [`::`](../operators/namespace-alias-qualifier.md), precedes a namespace alias, or follows the `global` alias. If you use `::` where `.` should be used to separate elements of a fully qualified name, the compiler emits one of **CS0431**, **CS0432**, **CS0687**, **CS7000*, or **CS8083**.